In general, buildings respectively have various kinds of windows or doors which are installed on openings of the buildings in order to block out the inside of the building from the outside, and in this instance, frames for supporting the windows or doors are classified into a wooden frame and a metal frame according to used materials. However, recently, the frames for windows or doors are made of plastic or synthetic resin such as PVC.
Now, the process of opening and closing a conventional sliding window will be described. When a user slides the window in a direction that the window is closed in a state where the user grasps a hand-grip of the window, rollers mounted on a lower end portion of the window rotate along a rail on a window frame. Accordingly, the window pane gradually approaches the window frame of the opposite side, and finally, stops by touching the window frame, so that the closing action of the window is finished.
However, the conventional sliding window having the window frame and the window pane has a problem in that it is difficult to clean the outside of the window pane for safety reasons in the case of high-rise apartments.
Moreover, in order to solve the above problem, various attempts have been made, but, even though a cleaning device is installed on the window, it causes several problems in that the external appearance is unbeautiful, the entire window becomes thicker, and an opening and closing rate of a ventilation window is deteriorated.